Accumulation of Copper and Zinc in Periphyton in Response to Dynamic Variations of Metal Speciation in Freshwater

Abstract

Although the free ion activity model (FIAM) has been well-established in laboratory studies, there remains the need for field data in order to validate the applicability of this model in natural systems. The objective of this study was to investigate the response of copper and zinc accumulation in periphyton to short-term variations in metal concentration and speciation in freshwater. During heavy rain events, dissolved Cu in the Furtbach stream increased from 40 to 118 nM, while dissolved Zn increased from 45 to 147 nM due to the release of metals from contaminated sediments. Increases in free copper and free zinc ions in the water (from 10(-14) to 10(-11.5) M for Cu2+; from 1 to 15 nM for Zn2+) were observed during the onset of heavy rain events. Periphytic algae collected from artificial substrates had an intracellular copper content (0.2-2.8 micromol/g dry weight (dw)) that varied as a function of the exchangeable copper in the water (labile form) rather than the free Cu2+. Intracellular zinc content (1.5-8.0 micromol/g dw) was found to follow the same trend as the free zinc ion concentration. Adsorbed Cu and Zn on periphyton showed a very dynamic response to variations in dissolved metal concentration. Different concentrations of dissolved manganese during the two time periods may affect the accumulation of zinc and copper by competition for metal uptake.

Relationship between the elemental composition of stream biofilms and water chemistry—a catchment approach

“…The different species of the metals determine their bioavailability for microorganisms (Meylan et al 2004;Kröpfl et al 2006). Intracellular zinc concentration was correlated to the concentration of zinc ions in the water, whereas intracellular copper may be incorporated from weakly complexed copper species (Meylan et al 2003(Meylan et al , 2004. Copper and lead are more easily available as ions .…”

“…Biofilms grown in streams with high concentrations of suspended matter also showed a high adsorption of dissolved elements (Knauer et al 1997;Campbell et al 2002). The bioavailability for microorganisms is determined by the metal speciation (Meylan et al 2003(Meylan et al , 2004. The toxicity depends on nutrient availability.…”

Modelling exchange kinetics of copper at the water-aquatic moss (Fontinalis antipyretica) interface: Influence of water cationic composition (Ca, Mg, Na and pH)

“…At the end of the accumulation step, a triplicate of bryophytes (approximately 700 mg fresh weight) were washed for 60 min with 50 mL of 1.0 mM EDTA (Na 2 -EDTA, Acros Organics, Geel, Belgium) to remove the metals adsorbed to the cell wall (Vázquez et al, 1999;Meylan et al, 2003;Fernandez et al, 2006). Copper in the EDTA solution is attributed to the extracellular metal content.…”

Formas de perdas de cobre e fósforo em água de escoamento superficial e percolação em solo sob aplicações sucessivas de dejeto líquido de suínos

“…Dessa forma, a especiação do metal em águas naturais seria fundamental para prever uma eventual toxidez e crucial para determinação de critérios de qualidade de águas. Isso porque, em condições naturais, a presença de altas concentrações de compostos orgânicos limita a disponibilidade e a toxidez de elementos como Cu 2+ (MEYLAN et al, 2003). Além disso, estudos de especiação de elementos transferidos do solo aos sistemas aquáticos são escassos na literatura de Ciência do Solo brasileira (BERTOL et al, 2007b).…”